The Driving Question Behind the Creation of the Calendar

Two thousand years ago, the Maya saw the sun go across the dark rift in late November. The sun travels across this section of the sky once a year and every year, it does it about 20 minutes later. This small shift is due to the wobble of the earth. This means that hundreds of years later the Maya saw the sun go through this section of the sky in early December, and hundreds of years after that, they saw it go through in mid-December and so forth. This apparent motion of the sun against the background stars is due to the orbit of the earth around the sun. Let's see how it works.

Here we see the dark rift as the “X” at the top. Imagine it to be very far away and fixed in its position. For our purposes, it is also fine to say that the sun does not move; in fact, we only need to be concerned with the motion of the earth. We see that once a year the earth orbits past the point where you can draw a line from the earth, through the sun and into the dark rift. As the earth moves to our right, the sun apprears to move to the left across the dark rift. But the sun is not moving; only the earth is moving. Nonetheless, once a year the sun will appear to be reborn as it appears to travels across the dark rift. By the way, the sun is in the dark rift for about three days and it is in the middle of the dark rift for one day.

The driving question behind the creation of the Long Count calendar was this: What year in the distant future - and remember, the Maya were asking this question two thousand years ago - what year in the distant future will have the sun in the middle of the dark rift on the same day as the winter solstice. That they were able to provide 2012 as the answer to this question is again, stunning.

In order, to do this, the Maya needed to measure the very slow shift due to precession. This is a very difficult problem for anyone to solve, but when you consider that the Maya did not have any high technology, it seems completely baffling. Could they have really done this? We'll learn the key to this in just a minute. But first, we have one more astronomical problem to consider: the special configuration of the sacred tree on December 21, 2012.